This invention relates generally to metal forming and, more specifically, to grinding.
Modern manufacturers carry as small an inventory of parts as possible to construct a product. By limiting the number of parts carried in inventory, a manufacturer can reduce overhead and minimize capital by removing the need for storage of excess inventory. This xe2x80x9cjust-in-timexe2x80x9d philosophy of manufacturing has become the world-wide standard for manufacturers of most products.
While xe2x80x9cjust-in-timexe2x80x9d production practices have saved millions of dollars, those same practices can be intensely expensive where no substitute exists for a needed part. Even with rigorous standards for quality control the possibility exists that a needed part may be outside of the specifications necessary. For example, imperfections may occur in component parts fabricated from exotic metals that require for formation high heat or pressure. Where such imperfections occur, economic realities may make modification of an existing, out-of-specification part more feasible than shutting down a manufacturing line while a part within specifications is fabricated.
An example of such an instance exists in the aircraft industry. In the construction of commercial airplanes, the price of the engines may comprise up to 25% of the total production costs. Each aircraft engine, after assembly, must undergo extensive testing for certification. The engines are delivered in their assembled state with appropriate attachment points for various connections to existing systems within the airframe.
Included in these connections is a duct for high temperature or high-pressure xe2x80x9cbleedxe2x80x9d gasses. Generally, this duct is made of inconelxe2x80x94a nickel chromium alloy with good oxidation resistance at high temperatures. This inconel duct is welded at one end to the engine and terminates at the other end with a large flange for mating onto a second duct where the engine mounts to the airframe. In the course of duct fabrication or subsequent welding the duct to the engine some deformation of the flange for mating to the airframe may occur. When this flange is no longer within tolerance of the specification for the mating junction, the known practice includes tearing down the engine; removing the inconel duct; replacing or machining the duct back into tolerances; re-welding the duct to the engine; reassembling the engine; re-testing and certifying the engine; and returning the engine to its mount on the airframe.
Due to the high cost of aircraft engines, mounting and installing the engines is the last substantial step before delivering a completed commercial airliner to its prospective owner. Under known techniques, a deformed flange delays the engine installation causing the airframe to sit idle, waiting for the rebuilt engine. That idle time is costly in terms of both resources as well as customer satisfaction.
There exists, then, an unmet need in the art for machining ducting in place without necessitating the disassembly of the engine.
The present invention allows for precision grinding of flanges without disassembly of the attached mechanism. In the case of aircraft engines, use of the present invention to correct defects in flanges removes necessity of tear-down, rebuilding, and subsequent FAA recertification of attached engines.
A portable precision flange grinder grinds a flange on a duct. The flange has an axis, a radius, and a periphery. A mount mounts the grinder within the duct. The mount attaches to openings at ends of the duct. A grinding wheel grinds a flange on a duct and arranged to rotate along a periphery of the flange. A first linkage translates the grinding wheel along an axis of the flange to bring the grinding wheel laterally in grinding contact with the flange. The first linkage engages with the mount along an axis of the flange. A second linkage translates the grinding wheel along a radius of the flange bringing the grinding wheel radially in grinding contact with the flange. The second linkage attaches to the first linkage. A bearing assembly rotates the grinding wheel about the periphery of the flange. The bearing assembly is attached to the first linkage.
In accordance with further aspects of the invention, the present invention can remove defects that have occurred in the course of mounting or transporting a larger mechanism to which the flanged piece is attached. According to one aspect of the invention, the flange is affixed to an aircraft engine. However, according to other aspects of the invention, the present invention machines any flange that is circular in shape. Further, the base plug seals of the component against contamination by grinding debris.
According to other aspects of the invention, the present invention is adaptable to any metallic flange. The present invention further operates on suitably rigid non-metallic materials, such as plastic, to the extent that such materials are susceptible to grinding operations.